Question

What is the difference between nerve net, nerve ring and nerve cord?

Answer 1

1. A nerve net consists of interconnected neurons lacking a brain or any form of cephalization
2. Nerve ring - a ring of concentrated nervous tissue about the pharynx of various invertebrate animals
3. Nerve cord- a single hollow tract of nervous tissue that constitutes the central nervous system of chordates and develops into the spinal cord and brain in vertebrates.

Cnidarians contain diffuse nerve nets (nerves are fiber -like bundles of neurons). Animals with distinct cephalization (annelids, arthropods, vertebrates) have a central nervous system (CNS) which consists of one brain and one (sometimes 2) longitudinal nerve chord(s). The nerves that connect the CNS with the rest of the body comprise the peripheral nervous system (PNS).